My car uses loads of juice! I'm just wondering if the oxygen sensor is knackered....

How would you go about testing it?... I've got a DIY AFR kit in the garage, if I wire that up will that tell me?...

 

plug your connectors together under your dash, look 4 3 slow flashes followed by 2 quick flashes

 

I cannot answer the question on how you can test it, but no an AFR wont tell you the Lambda is knacked cos it's reading from said Lambda.

Basically when a Lambda goes they see a lean mixture, so the ECU bungs more fuel in to make the Lambda read correct (but actually giving you a rich mixture). At this point the ECU will see the correct mix as will the AFR.

When they are totally knacked the ECU will give a CEL when running diagnostics, but they normally have to be totalled to do this, an under reading Lambda wont show up.

 

I reset the ECU a while ago and never had anything come back, but I didn't think it would pick up a knackered Lambda unless it had totally gone anyway.

Is there a way of checking using a voltage meter on the Lambda to see if the voltage it's giving out is within a certain range?...

 

yes there is but im not sure how to do it, IIRC you connect your meter up & basically when u press the accelarator the resistence should change, im sure someone else will come along to explain it more thoroughly, u should have got a fault code though, did u get the engine warm B4 you reset ecu, & how far did you drive afterwards??

 

voltage on the lambda signal wire (black on the Lambda or White with Silver band at ECU) should pulse from 0 - 600mV at idle.
When they are knackered you normally see a constant voltage i.e 3V

 

Thanks for that Scott, I'm gonna check it this weekend when I fit the AFR - I'll take the reading from the ECU itself.

 

no the AFR wont show much but mine has started to react slower than it used to

had mine 95WRX plugged in to the "yellow hand held diagnostic thingy" (sorry cant remember its name) and the lambda voltage was reading as expected

i changed the MAF tonight and now after the 10millionth ecu reset it finally came up with error 32 even tho its no errors have come up before.

so i'll be fitting a new lambda asap as my fuel bill has rocketed this week.

Mark

 

Excellent - my mobile mechanic mate has one of those plug in diagnostic jobs, I'm gonna ask him to pop round this weekend and check the lambda is within the correct working voltage

 

Select monitor??

It think thats what you mean

 

Cinders, what do you mean when you say your car uses loads of juice? Impreza fuel economy is never brilliant at the best of times, and if you drive it enthusiastically, it will have a hefty thirst.

Unfortunately the only real certain way to tell if your lambda sensor has deteriorated to any major degree is to replace it with a new one and see if the economy improves. Under these circumstances an AFR meter, provided it reads the correct voltage range, can indirectly highlight the failed sensor, as the new one will give a higher voltage on a wide-open throttle.

 

I've had the car about 4 months now and even if I drive it like a nun I can only manage about 80/100 miles from £20 of Optimax. The only mod the car has got is a different back box!...

Other people on the list say it's very low mpg!

 

Plus the cars done 65,000 now - surely the lambda probe must be nearing the end of it's life....

Can you clean them at all? Fitting a decat downpipe at the weekend so it'll be out anyway...